Flash memory is a non-volatile computer storage chip that can be electrically erased and reprogrammed. It was developed from Electrically Erasable Programmable Read-Only Memory (EEPROM) and must be erased in fairly large blocks before these can be rewritten with new data. Flash memories are generally classified into NOR and NAND types. The high density NAND type must also be programmed and read in (smaller) blocks, or pages, while the NOR type allows a single machine word (byte) to be written or read independently. The NAND type is primarily used in memory cards, USB flash drives, solid-state drives, and similar products, for general storage and transfer of data.
Package on Package (PoP) is an integrated circuit packaging technique to allow vertically combining discrete logic and memory Ball Grid Array (BGA) packages. Two or more packages are installed on top of one another, that are stacked, with a standard interface to route signals between them. This allows higher density and smaller physical size for electronic systems such a mobile telephone or personal digital assistant (PDA).
The Package on Package (PoP) module is a multi-chip module comprised of NAND flash and Low Power Dual Data Rate Synchronous Dynamic Access Memory (LPDDR SDRAM). Recently, NAND-flash memories have often been used as read only memories (ROMs) of mobile terminals.
A flash memory in an Integrated Circuit (IC) package such as for example a Package on Package (PoP) module can be utilized in transceivers such as GMR transceiver of a radio system for storing data. Certain requirements for Ground Mobile Radio (GMR) transceiver in radio systems have two areas of flash memory. Such flash memory 100 is depicted in FIG. 1 and has waveform area 102 and boot/recovery area 104. The user area 102 is writable from the outside but the boot/recovery area 104 is write protected.
Referring to FIG. 2, an issue with using the OMAP and the POP Memory Module is that the OMAP on power up has control over the Write Protect signal that goes to the PoP Memory Module Flash Area. These two devices are soldered together and there is no physical way of isolating the Write Protect signal that comes out of the OMAP to the PoP Module. The Write Protect signal is an output out of the OMAP. A need, therefore, exists for a way to employ Flash Boot and Recovery on the GLS Modem which uses the OMAP and PoP Memory Module is the ability of the Crypto Subsystem in the GMR radio to control the Write Protect signal to the PoP Memory Module Flash Area.